1. Field of the Invention
The present invention relates to a communication device that supplies electric power to another communication equipment by use of a transmission channel, a power supplying method therefor, and a power supply system.
2. Description of the Related Art
Importance has recently been imposed on battery safety, and safety measures have been sought. For instance, battery information, including information about whether or not a battery is a genuine battery and information about whether or not charging operation can be performed under ambient environment conditions, is first exchanged between a battery and a device before commencement of charging operation. Charging operation is commenced only when consensual validation is acquired.
As described in connection with; for instance, a Patent Document (JP-A-2009-273219), a method for controlling supplying power to a rechargeable battery connected to a charging circuit has already been proposed, and the method is now described by use of FIG. 12. Under the method, an internal power circuit (built in the charging circuit) that authenticates whether or not a connected rechargeable battery is rechargeable is instantaneously supplied with operable power. In contrast, the rechargeable battery is supplied with electric power whose current value is lower than that of electric power fed during boost charge; hence, the rechargeable battery is charged more slowly during normal charging operation than during boost charging operation. Therefore, even if a state of charge (SOC) of the rechargeable battery is empty, the battery can be safely charged.
Subsequently, when the rechargeable battery is charged up to a voltage that the battery becomes able to perform authentication through pre-charge operation (by means of a comparatively low current value), the rechargeable battery transmits rechargeable battery information to an internal circuit of the device by way of a charge authentication terminal (not shown). The internal circuit of the device acquired the information about the rechargeable battery performs processing for authenticating the rechargeable battery. When the internal circuit of the device determines that the rechargeable battery is rechargeable, an electric current of electric power fed to the rechargeable battery is made greater than that of electric power fed during the preliminary charge. Thereby, the rechargeable battery can be charged rapidly (see; for instance, Patent Document 1).
However, the technique described in connection with Patent Document 1 is limited to a relationship between the charging circuit and the rechargeable battery (i.e., a one-to-one relationship). Provided that a plurality of communication devices and electric devices are connected a supply line, a voltage applied to the supply line is shared among the plurality of electric devices. Therefore, the technique described in connection with Patent Document 1 cannot address the situation.